Millicent and her husband have been married for fifteen years. They met, fell in love, had two kids, and moved to the suburbs — the kind of life everyone assumes is exactly what it looks like. What nobody knows is how they've really kept the marriage alive: choosing someone to kill, together, about once a year.
They've gotten away with it twice already. But their newest target proves harder to erase than the others, a local detective starts connecting threads that shouldn't connect, and cracks begin to show in a partnership built entirely on secrets — including the possibility that the person hiding the most from you is the one lying next to you every night.